Incandescent electric lamp



(No Model.)

E. THOMSON. INCANDESGENT ELECTRIC LAMP.

No. 537,498; Patented Apr. 16, 1895.

VVn-NEEEEE UNITED STATES PATENT OFFICEe ELIHU THOMSON, OF SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO THE THOMSON-HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

INCANDESCENT ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 537,498, dated April 16, 1895.

Application filed May 23, 1892.

To all whom t may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States1'esiding at Swampscott, in the county of Essex, State of Massachusetts, have invented a certain new and useful Improvement in Incandescent Electric Lamps, of which the following is a specification.

My invention relates to incandescent electric lamps, and its object is to improve the details of the lamp and socket as hereinafter described and'particularly pointed out in the claims.

In the drawing, Figure l is a vertical sectional elevation. Fig. 2 is a top plan View of the lamp. Fig. 3 is a vertical section of the socket taken on a plane at right angle to Fig. l; and Fig. 4 is a vertical section of a moditied construction.

The glass bulb A is provided with a screwthreaded neck a, the threads being formed in a portion of the wall of the exhausted chamber of the lamp. This may be done by blowing the bulb in a screw-threaded metallic or other mold, after which the tube B, of glass, is inserted into the neck, and the ends of the tube and neck are sealed together; or, the tubular portion may be sealed to an unthreaded bulb, the base of which is then heated, placed in a mold, and blown or pressed into threads.

The tube B is closed at its inner end, but open at its outer end, thereby forming a reentrant pocket in the neck of the lamp. The leading-in wires C pass in through the inner end of the tube. Their outer ends are each electrically connected with a terminal, preferably arranged one within the other, as shown. The inner one D may be a headed pin extending into the tube. The outer one E may be a ring, anged if desired, and resting upon or within the mouth of the tube, and preferably less in diameter than the threaded neck of the bulb. The space around the pin and beneath the ring is filled with any suitable plastic or cementingsubstance F capable of withstanding the heat of the lamp, and of aiording a firm support to the terminals or contacts'D, E. I prefer to use plaster of paris; and in case it should be found that the tube B is broken by the expansion of this material Serial No. 434,077. (No model.)

when it sets, a few grains of cork or other inert elastic material may be mixed with the plaster; or a plug of cork G, may be used. The tube B is formed with internal irregularities b, such as grooves, depressions, knobs, beads, or the like, to serve as anchors for the plaster of paris; or it may be made with a narrowed mouth, to serve the same purpose. The shank of the pin D may also be roughened, serrated, or grooved, to give the plaster a Iirm hold upon it.

The socket is composed of a shell I-I, hav ing one end threaded, (preferably by helical corrugations when the shell is made of sheet metal) to receive the threads upon the lamp bulb. The body of the shell may be plain, and if preferred it may be somewhat larger than the threaded portion, to give ample room for the switch. The base of the shell is secured to the cap I, which has the usual tapped opening to enable the lamp t0 be fastened to a fixture. Inside the cap and the base of the shell is a plate K of insulating material, to which is secured the switch mechanism. This may be of any suitable design, but it is pre-- ferred to use a flat metallic spring L to bear upon the central contact D; said spring be` ing attached to the plate K or to a bracket L carrying a binding screw Z, by which one of the mains M is electrically connected with thespringL. TheothermainMisconnected, bya binding screwwith a bracket N, fastened to the plate K,and having depending ears in which is journaled the stem O. The ear u is slotted vertically to receive the inner journal of the stem, whereby said stem is permitted to have more or less vertical play. Mounted loosely on the stem is ablock P, having on each side of the stem arecess in which plays the end of a pin p driven transversely through the stem, and by which the block is caused to turn with the stem when the latter is rotated by the thumb piece O. Secured to the bracket N is a flat spring R, the free end of which presses against the block P. A tongue r on the end of the spring is guided in the slot in the ear n.

The parts are so proportioned that when the key is turned into the position shown in Fig. l, the block P stands vertically, with one IOO ehd bearing iipon the outer contact E. Vhen the block is turned at right angles to this po- 'sition, it does not touch the ring E, and the circuit is broken.

In the modification shown in Fig. t the la'mp bulb is screwed into a sleeve S which carries at its upper end a plate S' of insulating material,in the middle of which is a screw plug s. A curved spring plate s2 is secured to the under side of the plate and is in electrical connection with the sleeve S. This sleeve, its plate, the plug and the spring constitute an intermediate socket or adapter which serves to connect thelamp bulb shown in Fig. l with sockets of ordinary construction. The bulb screws into the sleeve S; the central contact D rests against the plug s', and the outer contact E bears against the spring S2. The sleeve in turn screws into the threaded shell T of the socket proper.

A shade can be readily attached to this lamp, by means of a nut U,of insulating material, such as porcelain or hard rubber adapted to screw upon the neck of the bulb or upon the socket, and having an external groove to receive the neck-hand of the shade support V.

The above described construction has many practical advantages. The contacts in the socket both press against the base of the lamp, holding it firmly in place by taking up all possible play between the lamp and the socket. The lamp base is stronger by reason of the screw-thread, and all strain comes directly upon the base instead of on a part to which the base is secured. The base cannot be severed without breaking the lamp. The large surface of the screw-threads gives sufficient friction to prevent the lamp from shaking loose. The outer shell of the socket is entirely unconnected with and insulated from the electrical circuit, without especial provision therefor. The shell can therefore be made of any material (insulating or not) capable of withstanding the heat of the lamp. This feature is of especial value in hastjT installations or in those for architectural elect.

The lamp is smaller, lighter, handsomer, and less expensive to make than any-lamp with which I am familiar.

What I claim as new, and desire to secure by Letters Patent, is-

l. Abulb foran incandescent electric lamp, having a portion kof its exhausted chamber formed with external screw-threads, substantially as set forth.

2. A bulb for an incandescent electric lamp, the neck portion of whose exhausted air chamber has a screw-thread formed on the material of the lamp, substantially as set forth.

3. A bulb for an incandescent electriclamp'-, having in its base a support for the filament projecting into the bulb, the surrounding Walls of the exhausted air-chamber being screw-threaded, substantially as set forth.

4. A bulb for an incandescent lamp, having a neck formed with screw-threads, and a supporting tube projecting into the bulb, and surrounded by the screw-threaded portion of said neck, substantially as set forth.

5. A bulb for an incandescent lamp, having a screw-threaded neck, and a supporting tube of smaller diameter inclosed within the screwthreaded portion thereof, substantially as described.

6. Abulb for an incandescent lamp, having a screw-threaded neck, forming part of the exhausted air-chamber, and asupporting tube connecting with the outer end of said neck, and projecting into said exhausted chamber, substantially as described.

7. The combination with an incandescent lamp bulb having a supporting tube, of metallic contacts, and a plastic or cement filling for retaining them in position, said filling being composed of plaster of paris mixed with cork, substantially as described.

S. The combination with an incandescent lamp bulb, having screw-threads formed in the wall of the exhausted chamber, of a socket threaded to receive said bulb, and insulated thereby from the electrical circuit, substantially as set forth.

9. An incandescent lamp having a contracted neck with a screw-thread formed on the material of the exhausted chamber of the lamp and insulated terminals on the base of said neck combined with a socket having inclosed insulated terminals adapted to make spring contact with the corresponding lamp terminals, and an outer metallic shell screwthreaded to receive the neck of thelamp, and insulated from the lamp by the material of the lamp and from the socket terminals by the insulating material to which said terminals are attached.

l0. The herein described method of making an incandescent lamp bulb, which consistsin sealing within the neck of the bulb a supporting tube closed at its inner end, thereby forming an airspace between the neck. of the bulb and said tube, placing the neck in a screwthreaded mold, and forming an external screwthread in said neck portion of the bulb.

In witness whereof I have hereto set my hand this 20th day of May, 1892.

ELIHU THOMSON. Witnesses:

JOHN W. GIBBONEY, BENJAMIN B. HULL.

l1 oo IOS 

